This invention relates to a lubricating device for a four stroke outboard motor and more particularly to a dry sump lubrication system for an outboard motor.
Although two cycle engines are normally utilized in the power plant in an outboard motor, there are some advantages to the use of four cycle engines for this purpose. However, one disadvantage with the four cycle engine is that the compact nature of an outboard motor makes it difficult to provide an adequate closed lubricating system for the engine. Specifically, it is necessary to provide an oil reservoir that will have a sufficient volume to accommodate long running periods and which will maintain a relatively low oil temperature. For a variety of reasons, not the least of which is the fact that the outboard motors generally have their engines operating with their crankshafts rotating about a vertically extending axis, the use of dry sump lubrication systems for outboard motor applications are very advantageous. A dry sump lubrication system permits the lubricant reservoir to have a large volume and also to be placed at a convenient location.
One of the problems in connection with the design of a lubrication system for an outboard motor is the fact that such motors are normally mounted on the transom of an associated watercraft for trim adjustment through a plurality of trim positions and also for tilting up out of the water during storage. Of course, the lubrication system must be capable of operating efficiently in all of the trim positions and also must be capable of accommodating the tilting up out of the water movement. This particular condition can be a problem because the abnormal orientation of the engine can give rise to the condition that lubricant will flow back from the reservoir into the engine.
In addition to this problem, when the outboard motor is tilted back down to its normal running condition, it must be inured that there will be adequate lubrication for the engine if it is started immediately. That is, if the oil or lubricant drains to a different part of the system, the oil must be returned to the area where the pump is to insure that the engine is adequately lubricated upon restarting.
Aside from the aforenoted problems, there is the additional concern that lubricant can flow from the dry sump tank back into the engine during periods of time when the engine is not running. This is a particular problem either when the orientation is changed, as aforenoted, or if the engine is shut off under conditions when a portion of the lubricant level lies above a lower portion of the engine.
Compounding the aforenoted problems is the fact that frequently outboard motors are detached from the transom of the watercraft and are laid on their side, front or back. Obviously, all of the aforenoted problems can be particularly acute when this condition prevails. The lubrication systems proposed of engines previously simply have not been capable of accommodating all of these conditions and solving all of the noted problems.
It is, therefore, a principal object of this invention to provide an improved lubricating system for an outboard motor.
It is a further object of this invention to provide a dry sump lubricating system for an outboard motor that insures that lubricant cannot flow into the engine when the engine is not running or in the event the orientation of the engine is changed.
It is also an object of this invention to provide a dry sump lubrication system for an outboard motor that will insure that the outboard motor is adequately lubricated if it has been displaced from its normal position when it was not running then is returned to a normal position and started.